Warren defeated Brown in a 2012 race that was the costliest in Massachusetts history. She said in an email to supporters that they helped her raise $40,000 for Shaheen over the weekend.

Warren faulted Brown for failing to agree to the so-called ``people's pledge'' in the New Hampshire race. Warren said Brown has ``signed on to get the dirtiest, most secretive help he can find'' to attack Shaheen.

Brown and Warren signed a similar pledge in 2012, limiting the outside money spent on television, radio and internet ads.

Brown has pointed to Shaheen's out-of-state fundraising, calling her demand for a pledge ``hypocritical and self-serving.'' (Associated Press)